The present invention relates to a gearshift transmission of a motor vehicle with a plurality of forward gears engageable by synchronizing clutches and a reverse gear, with the gear sets of the various gears being mounted on a drive shaft of a parallel output shaft and an auxiliary shaft and at least one output gear being formed by multiple utilization of existing gear pairs.
In a gearshift transmission of this kind, such as shown in German Patent Document 38 30 026, two forward gear pairs and two intermediate gears mounted on a countershaft are used to create reverse gear. The intermediate gears are connectable with one another in a torque-transmitting fashion by a shiftable clutch. One intermediate gear meshes with the fixed gear of first gear G1, the other intermediate gear with the idler gear of third gear G3. With the clutch engaged, the power flows from the input shaft of the transmission through the fixed gear of first gear G1 to the first intermediate gear, through the clutch to the second intermediate gear, to idler gear G3, and finally to fixed gear of G3 nonrotatably connected to the output shaft and meshing with idler gear G3. In this manner, the gear pair of the reverse gear that are otherwise usual can be eliminated.
An object of the invention is to eliminate at least one gear pair, even for forward gears, by using this principle of multiple utilization of gear pairs in order to reduce the overall length and manufacturing costs of the transmission.
This and other objects are achieved by the present invention which provides a gearshift transmission of a motor vehicle comprising a drive shaft, an output shaft parallel to the drive shaft, an auxiliary shaft, and a plurality of forward gears engageable by synchronizing clutches and a reverse gear. The gears have gear sets mounted on the drive shaft, the gear sets including gear pairs, with at least one of the gears being formed by multiple utilization of existing gear pairs. A high-reduction first gear is formed that includes the gear set of the reverse gear and a fixed gear mounted on the auxiliary shaft and meshing with the gear pair of a highest of the forward gears.
When, in order to create a high-reduction first gear, the power flow runs through the gear set of reverse gear and the gear pair of fifth gear, one gear pair for first gear can be eliminated. The overall length and manufacturing costs of the transmission are lower. The present invention lengthens the shaft of the reverse gear intermediate gear as an auxiliary shaft and mounts a fixed gear on it which meshes with the gear set of fifth gear. To engage first gear, the intermediate gear of reverse gear is connected by a half synchronizing clutch with the auxiliary shaft.
In certain embodiments of the invention, a second gear is additionally provided. For this purpose an additional idler gear is mounted on the auxiliary shaft, which meshes with the gear pair of third gear. To engage first gear, the intermediate gear of reverse gear is coupled to the auxiliary shaft, and to engage second gear the additional idler gear is coupled with the auxiliary shaft. To shift all gears, only one clutch needs to be actuated. The shift pattern is identical to the conventional H-pattern. A sixspeed transmission so designed requires only four gear pairs in succession for the forward gears. Since the overall length is extremely short, a transmission of this kind is best suited for installation crosswise on the front axle of a motor vehicle.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.